Abstract:

Support for medical and recreational marijuana legalization is on the rise, with more than half of states having passed medical marijuana laws, and recent polls showing the majority of the U.S. in support of legalization (Marijuana Policy Project, 2016). While critics of these laws often claim that they will lead to more crime, supporters assert the opposite- that allowing legal sale of marijuana would decrease crime by shrinking the illegal drug market. Previous research has analyzed the effects of the implementation of medical marijuana laws on crime rates, but this paper is the first to study how the size of the medical marijuana market affects crime rates. By using the medical marijuana patient registration rates across states from 1995 to 2015, I use a difference-in-differences approach to find that a one percent increase in medical marijuana registration rates decreases murder and robbery rates by 0.03% and 0.02%, respectively, and has no significant effect on other types of crime. These results show that increasing the legal availability of marijuana through medicalization could decrease murder and robbery rates, two crimes highly associated with the illegal drug trade.